Luminaires



K. FRANCK El' AL Nov. 26, 1957 LUMINAIRES 3 Sheecs-SheeiI 2 Filed April4, 1955 3 r H E ,Wm @MW .m O 5% zn .lpg A 2PZ/ Nov. 26, 1957 K. FRANCKETAL LUMINAIRES Filed April 4, 1955 5a' l do' 3 Sheets-Sheet 5 UnitedStates Patent LUMINAIRES Kurt Franck and Robert G. McPhail, Newark,Ohio, as-

signors to Holophane Company, Inc., New York, N. Y., a corporation ofDelaware Application April 4, 1955, Serial No. 498,951

7 Claims. (Cl. 24U-106) The present invention relates to luminaires andis more particularly directed to luminaires for corridor lighting.

The observer of a corridor light as normally mounted views the luminairefrom a very restricted zone along the corridor. As the observer cannotreadily avoid having the luminaire in the direct line of view, it isdesirable to obtain a very low brightness throughout the projected areain the restricted eld of view available.

In all other zones light may be sent in any direction whatever, that is,toward the walls, the floor and the ceiling, and full advantage can betaken of reflectances from these surfaces to achieve a harmoniousbrightness balance.

The present invention contemplates corridor lighting units havingprismatic light controlling elements which redirect the light in such amanner as to secure very low end brightness with transmission of lighttoward the ceiling and side walls lengthwise of the corridor. It alsocontemplates controlling laterally emitted light to effect ceiling andlower side wall illumination and the control of the lower angled lightto concentrate it on to the oor and spread it lengthwise of the iloor.

The accompanying drawings show, for purposes of illustrating the presentinvention, one embodiment in which the invention may take form, it beingunderstood that the drawings are illustrative of the invention ratherthan limiting the same.

In the drawings:

Figure 1 is a perspective view from below of the lighting xture bowlshowing the pattern of the external prismatic elements;

Figure 2 is a similar view of the portion of the plunger forming theinternal prismatic elements and indicating in reverse, the pattern ofthe same;

Figure 3 is a top plan view of the bowl showing in the upper leftquarter thereof, the inner prism pattern;

Figure 4 is an inverted plan view of the bowl showing in the upper rightquarter thereof, the outer prism pattern;

Figure 5 is a side elevational view with parts in section on the line5-5 of Figs. 3 and 4;

Figure 6 is an end elevational view with parts in section on the line6-6 of Figs. 3 and 4;

Figure 7 is a perspective view of a corridor with the lighting fixturebowl mounted at the ceiling line; and

Figure 8 is a photometric chart illustrating the light distribution fromthe bowl.

The refracting bowl B shown herein is adapted to be mounted as indicatedin Figure 7 at the ceiling line of a corridor so that its ends are inthe normal lield of view for persons facing lengthwise of the corridorand at a suitable distance from the luminaire. The bowl has a relativelylarge projected area in this eld of view. The bowl is ofpseudo-rectangular shape when viewed by itself and is mounted with itslongitudinal axis of symmetry lengthwise of the corridor. Its length towidth ratio is approximately 3:2 and its length to depth ratio,approximately 3:1.

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In the drawings the horizontal mounting ange of the bowl is indicated at10, the substantially vertical, substantially flat sides at 11, 11,convex ends 12, 12, and the relatively shallow bottom, convexlongitudinally and transversely at 13. The bowl is symmetrical onopposite sides of the longitudinal vertical median plane 14, 14 (Fig. 6)and on opposite sides of the transverse vertical median plane 15, 15(Fig. 5). The ends 12 are toroidal, generated about a center near theintersection of planes 14-14 and 15--15 and a second center above theange at the other end. The bottom 13 is also toroidal with a very longradius of curvature longitudinally. The corners are iilled in atsuitable radii. The bowl is designed to receive a lamp having a lightsource LC in these planes, at the elevation indicated by the cross inFigures 5 and 6.

Viewed externally the refractor has several panels occupied by prismaticelements and indicated by Roman numerals as follows: panels I--I at theends 12, 12 provided with light splitting prisms 16 extending across thesame; panels II centrally disposed on the bottom 13 near thelongitudinal median plane 14, 14, Vand provided with transverse prisms17; panels III on the bottom 13 adjacent the sides 11, 11 and providedwith longitudinal prisms 18; vpanel IV of rectangular shape, central ofthe bottom 13 and provided with wide longitudinal prisms 19; panels V-Valong the sides 11, 11 and provided with horizontal prisms 20; andpanels VI at the corners and provided with transverse prisms 21.

Viewed internally, the bowl has panels similarly located and indicatedby corresponding Roman numerals I', Il', III', IV', V and VI',respectively. Inside panels I and II are provided with light splittingprisms 16' and 17', respectively. Inside panels III are provided withnarrow transverse flutes 18. Inside panel IV is provided with widetransverse utes 19. Inside panels V' are provided with vertical flutes20'. Inside panels VI are provided with longitudinal llutes 21.

The action of crossed prisms 16, 16' in the panels I and I' is such asto spread the light laterally as indicated by the rays 31, 32 of Figure3 and up and down, as indicated by the rays 33, 34, Figure 5. Theresultant of the double spreading is to place light on the ceiling, theoor and on distant corridor walls, with little light escaping toward theperson in the corridor to produce low brightness. This prismaticconstruction forms the subject matter of a separate application forLetters Patent Ser. No. 498,952, tiled April 4, 1955.

The inner prisms 17' of panels II' are light splitting prisms and theouter prisms 17 of panel II depress the light as indicated at 35. Theycontinue the light lowering action of the prisms 16 so as to place acontinuous pattern of light lengthwise of the corridor oor. The outerprisms 18 and 19 on panels III and IV and opposed ilutes 18 and 19 actto lower the light toward the oor as indicated at 36 and 37 (Fig. 6) anddiffuse it lengthwise of the corridor. The horizontal prisms 20 on thesides of the refractor split the light, sending some of it up, asindicated at 38 for ceiling illumination, and lowering it, as indicatedat 39, for illuminating the lower side walls of the corridor.

The full line photometric curve 40, Fig. 8, taken along the aisle showsthat a substantial portion of the light is raised toward the ceiling andvery little light is emitted in the direction in which an observer viewsa corridor lighting unit. With a watt lamp the brightness toward such anobserver is less than one candle per square inch. The dash line curve 41shows that very little light escapes sidewise at and above thehorizontal. The dominant light output is concentrated to be less than 45from the nadir, both longitudinally and laterally.

Since itis obvious that the invention may be embodied in other forms andconstructions within the scope of the claims, we wish it to beunderstood that the particular form shown is but one of these forms, andvarious modications and changes being possible, we do not otherwiselimit ourselves in any way with respect thereto.

What is claimed is:

l. A corridor lighting luminaire comprising a bowl symmetrical aboutvertical, longitudinal and transverse median planes, and a concentratedlight source at the intersection of the planes and below the upper edgeof the bowl, the bowl having substantially vertical parallel sidesshorter than the length of the bowl and provided with horizontal lightsplitting prisms which deviate light from the source upwardly anddownwardly to light the corridor walls alongside the luminaire, the bowlhaving ends which extend from the ends of the sides to the longitudinalmedian plane, converge downwardly from its upper edge, and are providedwith prisms which deviate light from the source away from thelongitudinal median plane and above and below the horizontal forlighting the ceiling and corridor walls more remote from the luminaireand reducing brightness to an observer in the corridor at normal anglesof view, the bowl having a rotund bottom provided with longitudinallight lowering prisms to reduce the transverse spread of downward lightfrom the source and transverse dilusing flutes to increase thelongitudinal spread of light.

2. The luminaire claimed in claim 1, wherein the longitudinal prisms onthe central portion of the bottom are relatively large and of smallrefracting power and the longitudinal prisms in the bottom outside thecentral portions thereof are relatively small and of greater refractingpower.

3. The luminaire claimed in claim l, wherein the said ends are outwardlyconvex in both horizontal and vertical planes and the ends have lesserradii of curvature in vertical planes than the bottom.

4. Means for lighting the ceiling, side walls and floor of a corridor orthe like, and avoiding high brightness in the normal line of sightlengthwise of the corridor, comprising a concentrated light sourcemounted adjacent to but below the ceiling level and a refractorintercepting all light from the source which would otherwise fall onsaid ceiling, side walls and oor and redirecting the same, the refractorbeing in the form of a bowl closed at the bottom and symmetrical onopposite sides of median longitudinal and transverse planes through thesource, said bowl having generally parallel sides opposite the sourceand parallel with the corridor wall, the said sides being provided withlongitudinally extending prisms which deviate light upwardly anddownwardly for nearby ceiling and side wall lighting, ends connectingthe sides and provided with light splitting prisms which raise and lowerthe light for the ceiling and remote floor areas and laterally deviatethe light for lighting remote side wall areas, a bottom provided withlongitudinal light depressing prisms which reduce transverse divergenceand transverse diffusing ribs which spread light longitudinally andplace such light on the oor, and between the ends and bottom cornerportions with prisms which reduce the longitudinal divergence of theemitted light and increase its lateral divergence.

5. A refracting bowl symmetrical on opposite sides of longitudinal andtransverse vertical planes and with a length-width ratio ofsubstantially 3:2 and a length-todepth ratio of substantially 3:1, thebowl having substantially at parallel sides, downwardly convergingrotund ends with horizontal radii of curvature of substantially 1/2 thelength of the bowl, a shallow dished bottom portion and corner formingfillets of relatively small radius connecting the ends and bottom, theends being provided with internal vertical light splitting prisms andexternally generally horizontal light splitting prisms, the sides beingprovided with horizontal external light splitting prisms and internalvertical light spreading flutes, the bottom being provided withtransverse ilutes opposed to light concentrating prisms which extendpart way to the ends of the bottom, the portion of the bowl between thesaid ends and the said prisms on the bottom and adjacent thelongitudinal plane being provided with longitudinal light splitting andtransverse light lowering prisms, the portions laterally of the lastmentioned portion being provided with light spreading prisms.

6. A direct lighting bowl symmetrical on opposite sides of verticallongitudinal land transverse planes at right angles to one another andhaving substantially vertical parallel sides, toroidal ends eachgenerated about a vertical laxis in the longitudinal plane adjacent tothe transverse plane and a horizontal axis above the opposite end, atoroidal bottom extending from side to side with relatively shorttransverse radii of curvature and relatively long longitudinal radii ofcurvature, and corners with shorter radii of curvature than the verticalradii of curvature of the ends, the ratio of length to width beingsubstantially 3:2 and of length to depth vbeing substantially 3:1, thesaid sides having light splitting prisms to direct light up and down,the ends having light splitting prisms which direct light up and downand laterally, the bottom having longitudinal prisms which reduce thetransverse spread of light and transverse flutes which increase thelongitudinal spread of light, the corners having external transverselight lowering prisms and internal, longitudinal light: spreadingprismatic elements.

7. An elongated refracting bowl having a horizontal upper edge withsubstantially vertical parallel sides, rounded ends convergingdownwardly, and a bottom externally convex both longitudinally andtransversely, prismatic means in the sides to transmit light originatingfrom a source in the center of the bowl upwardly and downwardly at theexpense of horizontal transmission, prismatic means in the ends totransmit light from the source upwardly, downwardly and laterally at theexpense of transmission longitudinally and horizontally, prismatic meansin the bottom to reduce the transverse divergence of light from thesource and spread it longitudinally, and prismatic means in the ends forspreading light laterally and lowering it.

References Cited in the le of this patent UNITED STATES PATENTS1,426,280 Dorey Aug. 15, 1922 1,731,714 Dorey oct. 1s, 1929 2,280,160Roiph et a1 Apr. 21, 1942

